Strange Mini Solar System Found

starexplorer writes "In 1990, Penn State's Alex Wolszczan found the first exoplanets. But he never got much credit from mainstream researchers, because his planets (3 of them, roughly Earth-sized) orbit pulsars and hold no chance for harboring life. Now he's found a 4th object on the outskirts of the system, SPACE.com is reporting. Call it a planet, call it an asteroid, Wolszczan says, but call the setup a dark, eerie twin of the inner half of our solar system. Also in the same story, news of a brown dwarf just 15 times the mass of Jupiter that has a planet-making disk of stuff around it. Together, more problems for astronomers, who still don't have a basic definition for the word planet or a firm idea of what separates planets from stars."

Comments

TMBG

[angst7]

I think They Might be Giants defined what it was to be a star fairly well.

"The sun is a mass of incandescent gas
a giagantic nuclear furnace..."

Re:TMBG

[Anonymous Coward]

Singing Science Records

The Ballad of Sir Isaac Newton is also not to be missed.

Planets from stars?

[hobbesmaster]

Someone please correct me if I'm wrong or over generalizing, but planet vs stars: stars have fusion, planets dont. Hence, a gas giant like jupiter is a planet but a brown dwarf is a star (there is SOME fusion going on, or there was in the past).

Planet vs planetoid is another matter altogether... I'd love to know if theres been a 'real' standard proposed - regardless of whether pluto/charon are planets/moon or not.

Re:Planets from stars?

[Scott7477]

As far as a definition I found this:

"Working Group on Extrasolar Planets
Defintion of a "Planet"

POSITION STATEMENT ON THE DEFINITION OF A "PLANET"

WORKING GROUP ON EXTRASOLAR PLANETS (WGESP) OF THE INTERNATIONAL ASTRONOMICAL UNION

Created: February 28, 2001

Last Modified: February 28, 2003

Rather than try to construct a detailed definition of a planet which is designed to cover all future possibilities, the WGESP has agreed to restrict itself to developing a working definition applicable to the cases where there already are claimed detections, e.g., the radial velocity surveys of companions to (mostly) solar-type stars, and the imaging surveys for free-floating objects in young star clusters. As new claims are made in the future, the WGESP will weigh their individual merits and circumstances, and will try to fit the new objects into the WGESP definition of a "planet", revising this definition as necessary. This is a gradualist approach with an evolving definition, guided by the observations that will decide all in the end.

Emphasizing again that this is only a working definition, subject to change as we learn more about the census of low-mass companions, the WGESP has agreed to the following statements:

1) Objects with true masses below the limiting mass for thermonuclear fusion of deuterium (currently calculated to be 13 Jupiter masses for objects of solar metallicity) that orbit stars or stellar remnants are "planets" (no matter how they formed). The minimum mass/size required for an extrasolar object to be considered a planet should be the same as that used in our Solar System.

2) Substellar objects with true masses above the limiting mass for thermonuclear fusion of deuterium are "brown dwarfs", no matter how they formed nor where they are located.

3) Free-floating objects in young star clusters with masses below the limiting mass for thermonuclear fusion of deuterium are not "planets", but are "sub-brown dwarfs" (or whatever name is most appropriate).

These statements are a compromise between definitions based purely on the deuterium-burning mass or on the formation mechanism, and as such do not fully satisfy anyone on the WGESP. However, the WGESP agrees that these statements constitute the basis for a reasonable working definition of a "planet" at this time. We can expect this definition to evolve as our knowledge improves."

It looks like this is as close as we're going to get.

Re:Planets from stars?

[Rei]

It's not that simple. Do you say "If there was ever a single Dt-Dt reaction, it's a star", or do we require continuous reactions? It's hard to put an exact cutoff on the sequence from planets to main sequence stars.

All of the bodies get some heat from gravitational collapse as they condense. Once you get enough heat and pressure in a small enough area, you can get Dt-Dt fusion; when there is a "significant" amount, it's called a brown dwarf. However, a relatively small amount of hydrogen is deuterium. As it gets hotter and denser, you begin to get other types of fusion, and you end up with a main sequence star.

The planet/moon distinction becomes even harder when you can't tell exactly what's a planet or star. Once we get to some of these "huge jupiters", there will undoubtedly be debates as to whether there is a measurable amount of Dt-Dt fusion going on or not.

Mini solar system

[Scott7477]

How can this professor not be considered mainstream?
He's on the faculty at Penn State! Sounds like he must have ticked off the wrong people at some point in his career. Maybe he needs to hire a PR person.
I would say that finding a planet orbiting any star would be significant news, regardless of whether said planet might harbor life.

semantics

[Anonymous Coward]

semantics seperates planets from stars from asteroids... Our language, not reality...

Planet Definition

[FiReaNGeL]

Astronomers don't have a planet definition? Here's one! Planets are round, asteroids aren't! How's that ? :)

Definition

[null etc.]

...or a firm idea of what separates planets from stars.

Space. Quite a bit of it, I hope.

Oh, you meant what criteria separates planets from stars?

Well, I definitely would much rather live on one than the other. Is that a good definition?

Re:Definition

[hcdejong]

Planet X
Ah, but then we'd have to send...

Duck Dodgers in the 24 1/2th Century!!!

Re:Superman

[Rei]

I would love to see some of these extrasolar systems; the more we see, the more variety it looks like there is in the universe. "Hot jupiters" which orbit right close to their stars and even possibly exchange matter; the heat swells them up to many times their normal size. Brown dwarfs which give their closest moons enough light to possibly harbor life, while burning their deuterium slowly. Supercomets - planet-sized cometary bodies with huge comas. Planets without stars. "Water worlds" - bodies like Uranus or Neptune in a hotter orbit. And all sorts of other things.

I hope some day humans can see them in person. :)

No chance of life?

[suso]

because his planets (3 of them, roughly Earth-sized) orbit pulsars and hold no chance for harboring life.

I wish people wouldn't say things like this. Humans barely have a grasp on what life really is and what conditions it can exist under, especially off our own planet. So how could we make a judgement that life couldn't exist around a pulsar, despite its homo-sapien threatening conditions.

Re:No chance of life?

[vwjeff]

Acutally there are only two forms of life possible.

According to whom?

The only life we can be certain of is our own. Even then I sometimes wonder if I really exist. I guess I must because I am posting this, or am I?

How insensitive!

[Anonymous Coward]

..a brown dwarf just 15 times the mass of Jupiter..

Please, "African American little person with a weight problem" is a little more appropriate and a lot less offensive, don't you think? Sheesh.

Well Obviously

[Madcapjack]

Well Obviously this old dying star system is the original home of our species. We're just the descendents of the marooned colonists who found that their pyramid space-ships had suddenly (and quite inexplicably) turned to stone.

Go figure.

Stars generate energy

[Man in Spandex]

At least according to Wikipedia

Scientifically, stars are defined as self-gravitating spheres of plasma in hydrostatic equilibrium, which generate their own energy through the process of nuclear fusion.

Using this simple definition, it seems to apply to most stars out there? Correct me if I'm wrong or if the definition provided isn't accurate enough.

Re:Stars generate energy

[YU Nicks NE Way]

That works quite well for objects above about 25 Jovian masses. (In isolation, yadda yadda yadda) At that size, the body is large enough to support sustained thermonuclear fusion of species other than D+D->He3. Such bodies quickly heat up, becoming true red dwarf stars.

Object smaller than about 13 Jovian masses never exhibit any sustained fusion. Those objects are planets if they orbit a star or a stellar remnant. (They are "sub-brown dwarfs" if they don't orbit a star.)

Objects that sit between the 13 and 25 Jovian mass boundaries are in a grey area. They do exhibit sustained fusion, but only of D+D pairs. There isn't much deuterium around, though, so they don't ever heat up very much. Moreover, since they never engage in H+D->T and H+T->He3 fusion, they don't engage in the fusion reactions which are the signature of "real" stars. These are brown dwarfs -- not planets, because they do heat themselves up with fusion reactions, but not stars, either, because they don't fuse H.

The definitive definition

[Profane MuthaFucka]

A planet:
-is a non-fusor
-has sufficient mass to be roughly spherical due to gravity
-orbits a fusor
-isn't already referred to as any other type of object by convention
-isn't associated through orbital composition or other general characteristics with another general group of non-planet objects (i.e. Vesta, though spherical, is associated with other objects known as asteroids, which are not massive enough to be spherical, and are therefore not planets. Vesta also is not a planet, because of the previous rule. It is by convention known as an asteroid, therefore it's not a planet.)

My source for this definition is myself, and I deem it sufficient for sparking a major discussion, and possibly for other things as well.

Why on Earth does the name matter?

[TechyImmigrant]

We started out with a limited number of names for things. Planets, stars, the sun. They we found some more things like comets and asteroids.

Now we've found lots of things that come in between, requiring a different form of classification. The only problem is that people are trying to squeeze the definition of things we know about into a limited naming set.

To name something doesn't mean we understand it and being unable to name something doesn't mean we don't understand it.

People should stop worrying and be happy that we can describe these objects to a higher level of detail than can be described using the existing names we had for things floating in space.

Re:Why on Earth does the name matter?

[T-Ranger]

Hence forth, all space boddies will be known as "thingies".

What separates planets from stars

[pronobozo]

"who still don't have a basic definition for the word planet or a firm idea of what separates planets from stars."


One is on fire and one isn't.

Now hand over my research grant.

It shouldn't be that hard.

[Corbin Dallas]

problems for astronomers, who still don't have a basic definition for the word planet or a firm idea of what separates planets from stars.

It's not as sexy as having a word like "planet", but all this confusion could be eliminated with a basic classification system that took into account distinguishing characteristics besides just it's mass.

As an example, one could define these objects through two primary attributes: The body's mass and the mass of that which it orbits. As I don't have exact mass data at hand, this example will use the following over-simplifications:

S = Solar Mass
G = Gas Giant Mass
R = Rock Planet Mass
M = Minor Mass ( appx Phobos to Pluto )
A = Asteroid Mass
D = Debrit ( 1m or smaller )

Of course, the real system would use exact scientific measurments rather than these crude examples.

Earth = SR ( Rock Planet Mass orbiting a Solar Mass )
Jupiter = SG ( Gas Giant Mass orbiting a Solar Mass )
Pluto = SM ( Minor Mass orbiting a Solar Mass )
Titan = GR ( Rock Planet Mass orbiting a Gas Giant Mass )
etc
etc

You could even create a symbol to represent the galactic center, which could be used in relation to stars and other free roaming bodies. Binary stars can be represented using SS, since they're orbiting each other.

Anyway, the point is that you can not come up with solid definitions of these bodies on mass alone. Take into account other major factors as this example does.

Re:Solar? It's not Solar at all, morons

[RubberDogBone]

It's that reporter for Space.com, Robert Roy Britt.

He has a habit of using the word "solar" for non-solar topics, and of course the Space.com stories end up on the wire services and are repeated by hundreds of TV talking heads. All that does is make the problem worse. It's bad enough that most people don't even know the name of their star. We don't need them attaching that name to totally unrelated objects.

Here's an unedited quote from him regarding a complaint on the same subject from one of his previous stories:

Thanks for your note. You are correct in the strict sense, but astronomy and language are evolving. We now know of many other systems that look familiar. And many astronomers have come use the term "solar system" to describe other planetary systems. It's becoming a bit like Kleenex in its generic usage.

I'm all for accuracy, but I think also that language is fluid, and if astronomers use the term interchangeably, then I think it's best I do so,
too. I also find it the most convenient term to convey a system of planets with a central star -- and there are hints of lone, wandering planets not
hosted by a star, so a distinction is helpful (at least until the latter situation is sorted out). I appreciate hearing from you because notes like
yours help me frame my approach to writing.

Definition

[GrabtharsHammer]

planet n.
Big lump of stuff, roundish, spinning a bit, usually orbiting a, um, star thingy. Might have aliens on, but probably not. Probably.